Import LESS from server

Question

In my ASP.NET MVC application I have an action that returns LESS variables.

I would like to import these variables into my main LESS file.

What is the recomm

Answer 1

I found the easiest solution was to implement IFileReader.

The implementation below makes a HTTP request to any LESS path prefixed with "~/assets", otherwise we use the default FileReader.

Note that this is prototype code:

public class HttpFileReader : IFileReader
{
    private readonly FileReader inner;

    public HttpFileReader(FileReader inner)
    {
        this.inner = inner;
    }

    public bool DoesFileExist(string fileName)
    {
        if (!fileName.StartsWith("~/assets"))
            return inner.DoesFileExist(fileName);

        using (var client = new CustomWebClient())
        {
            client.HeadOnly = true;
            try
            {
                client.DownloadString(ConvertToAbsoluteUrl(fileName));
                return true;
            }
            catch
            {
                return false;
            }
        }
    }

    public byte[] GetBinaryFileContents(string fileName)
    {
        throw new NotImplementedException();
    }

    public string GetFileContents(string fileName)
    {
        if (!fileName.StartsWith("~/assets"))
            return inner.GetFileContents(fileName);

        using (var client = new CustomWebClient())
        {
            try
            {
                var content = client.DownloadString(ConvertToAbsoluteUrl(fileName));
                return content;
            }
            catch
            {
                return null;
            }
        }
    }

    private static string ConvertToAbsoluteUrl(string virtualPath)
    {
        return new Uri(HttpContext.Current.Request.Url, 
            VirtualPathUtility.ToAbsolute(virtualPath)).AbsoluteUri;
    }

    private class CustomWebClient : WebClient
    {
        public bool HeadOnly { get; set; }
        protected override WebRequest GetWebRequest(Uri address)
        {
            var request = base.GetWebRequest(address);
            if (HeadOnly && request.Method == "GET")
                request.Method = "HEAD";

            return request;
        }
    }
}

To register the reader, execute the following when your application starts:

var configuration = new WebConfigConfigurationLoader().GetConfiguration();
            configuration.LessSource = typeof(HttpFileReader);